The pulsatile, episodic and nychthemerally repetitive nature of hGH, hPRL, pubertal hLH, ACTH and the circhorally pulsatile character of hFSH and hLH indicate that these hormones, and in turn their hypothalamic release factors, are probably driven by neural pulses across the sleep-wake cycle, often in a way that does not conform solely to time-honored feedback setpoint concepts. We have presented evidence in re hGH that sleep-wake, genetic, ontogenetic, and perhaps rhythmic biologic clock determinants may modulate pulse generating neurons in addition to substrate and hormonal feedback. Here we propose to broaden our studies of hGH release in sleep in re normal patterns, normal physiology and release in disease states to include that of hPRL, hLH, and hFSH and their release across repetitive sleep-wake cycles. Our short sample interval - long study period technique allows a view of the important but neglected time dimension in release of the tropins of growth and maturation. A clear display of what normal release patterns are, as influenced by age, sex, puberty, maturity, menstrual cycle, sleep-wake cycle, and aging will result. A second aim is to examine feedback, sleep, genetic, ontogenetic and rhythmic determinants as physiologic modulators of release. A third aim is to learn to discriminate patterns of disease from those of normal and perhaps hypothalamic "input" disease from primary pituitary disease, and to better assess the effectiveness of their therapy in physiologic terms.